Stanford developes passive panel that cools without using power
April 16, 2013 1:44 AM Subscribe
Does it two ways. One: Reflects sunlight like a mirror to keep from heating up structure. Two: Uses a nano-patterned material that radiates infra-red heat (which it gets from being part of the building) at the wavelengths that penetrate the atmosphere without being absorbed. The reverse is what powers the well know greenhouse effect. They are claiming a net cooling of 100 watts per square meter with the panel. All without using power.
Unfortunately they don't work when dirty so you'd need a system to keep them clean that is cheap and doesn't use too much water.
posted by atrazine at 2:20 AM on April 16, 2013
posted by atrazine at 2:20 AM on April 16, 2013
Anyone able to supply a copy of the paper for the purposes of academic discussion?
posted by Joe in Australia at 2:28 AM on April 16, 2013
posted by Joe in Australia at 2:28 AM on April 16, 2013
atrazine, we've already invented that, it's called washing.
posted by mek at 2:31 AM on April 16, 2013 [4 favorites]
posted by mek at 2:31 AM on April 16, 2013 [4 favorites]
So this implies either no building insulation, or some sort of plumbing, right? Otherwise how does the building heat get to the panel.
This also sets off my Laws of Thermodynamics alarm, but it might need to be recalibrated for nano materials. Can some materials science person comment on wavelength-dependent emissivity please?
posted by ryanrs at 2:31 AM on April 16, 2013 [2 favorites]
This also sets off my Laws of Thermodynamics alarm, but it might need to be recalibrated for nano materials. Can some materials science person comment on wavelength-dependent emissivity please?
posted by ryanrs at 2:31 AM on April 16, 2013 [2 favorites]
Of course, it will turn out that making these panels requires vast amounts of electricity and rare materials, and the panels will release deadly gases when they decay.
I've gotten used to the fact that any conversation about world-saving technology inevitably turns into that Simpsons bit where the Frogurt is also cursed.
posted by Shepherd at 2:50 AM on April 16, 2013 [32 favorites]
I've gotten used to the fact that any conversation about world-saving technology inevitably turns into that Simpsons bit where the Frogurt is also cursed.
posted by Shepherd at 2:50 AM on April 16, 2013 [32 favorites]
As far as I can tell from reading the paper, they haven't actually made this material, just simulated it numerically. It's rather nifty: almost totally reflective in the solar radiation regime, but radiating it's own heat energy in the IR range where the atmosphere is nearly transparent so it radiates it's own heat directly into space.
We have no idea how difficult or expensive it would be to manufacture: the authors handwave that existing large scale production of nanoscale structures has been demonstrated, so therefore their new structure could plausibly be mass produced, but can give no idea of what the costs would be.
The major practical problem is going to be that if it's not kept very clean, the dust and dirt will absorb both solar radiation and IR radiation from the panel, potentially eliminating the cooling effect altogether. It may well be that the costs involved in keeping the panel clean outweigh any benefits: it will all depend on the details.
posted by pharm at 2:59 AM on April 16, 2013 [10 favorites]
We have no idea how difficult or expensive it would be to manufacture: the authors handwave that existing large scale production of nanoscale structures has been demonstrated, so therefore their new structure could plausibly be mass produced, but can give no idea of what the costs would be.
The major practical problem is going to be that if it's not kept very clean, the dust and dirt will absorb both solar radiation and IR radiation from the panel, potentially eliminating the cooling effect altogether. It may well be that the costs involved in keeping the panel clean outweigh any benefits: it will all depend on the details.
posted by pharm at 2:59 AM on April 16, 2013 [10 favorites]
This also sets off my Laws of Thermodynamics alarm, but it might need to be recalibrated for nano materials.
No need. The Earth is not a closed system. If you can get the panel to emit radiation at a frequency that is transparent to the atmosphere, you'll have an object at about 300K radiating to 3K free space.
Radiative cooling works very well at night, when there isn't any clouds and doubly so when there's no wind. I'm wondering what frequency they're radiating at.
I'm also wondering how it handles clouds.
posted by eriko at 3:03 AM on April 16, 2013 [3 favorites]
No need. The Earth is not a closed system. If you can get the panel to emit radiation at a frequency that is transparent to the atmosphere, you'll have an object at about 300K radiating to 3K free space.
Radiative cooling works very well at night, when there isn't any clouds and doubly so when there's no wind. I'm wondering what frequency they're radiating at.
I'm also wondering how it handles clouds.
posted by eriko at 3:03 AM on April 16, 2013 [3 favorites]
What was that coating that came out last year that ketchup people wouldn't put on the inside of bottles because then people could actually get to every last drop of it? I wonder if it could be combined with this to help keep these hypothetical panels clean. Ah, it seems it's called LiquiGlide.
posted by Mizu at 3:06 AM on April 16, 2013 [4 favorites]
posted by Mizu at 3:06 AM on April 16, 2013 [4 favorites]
I'll upload the emissivity graph at least. Fair use in action!
posted by pharm at 3:07 AM on April 16, 2013 [1 favorite]
posted by pharm at 3:07 AM on April 16, 2013 [1 favorite]
I'm waiting for the part where they explain that it takes 1.21 gigawatts of power to produce 1 square meter of the miracle material.
posted by ShutterBun at 3:08 AM on April 16, 2013
posted by ShutterBun at 3:08 AM on April 16, 2013
Don't let anyone gets their hopes up, ever. Buncha Debbie downers around here.
posted by BrotherCaine at 3:22 AM on April 16, 2013 [11 favorites]
posted by BrotherCaine at 3:22 AM on April 16, 2013 [11 favorites]
It's neat, but there are a lot of ways to keep a building cool if you are actually serious about it. We only abandoned these techniques like 50-100 years ago, when cheap energy came around. We could just go back to them.
posted by DU at 4:07 AM on April 16, 2013 [10 favorites]
posted by DU at 4:07 AM on April 16, 2013 [10 favorites]
Don't let anyone gets their hopes up, ever. Buncha Debbie downers around here.
I dunno. It's a really cool idea, and I'm always happy to see Wngineering students working on something neat, but there is this persistent idea that we can engineer our way out of any hole we can dig. I think that idea leads people toward "We don't need to change how we live; sure, climate change turned out to be real, but Science! will save us and our lifestyle. Just give it a few more years." I like Science! As much as the next guy, but I've watched fusion be "just a few years away" for my whole life, and I'm unconvinced. Is that being a downer or just realistic?
posted by GenjiandProust at 4:14 AM on April 16, 2013 [13 favorites]
I dunno. It's a really cool idea, and I'm always happy to see Wngineering students working on something neat, but there is this persistent idea that we can engineer our way out of any hole we can dig. I think that idea leads people toward "We don't need to change how we live; sure, climate change turned out to be real, but Science! will save us and our lifestyle. Just give it a few more years." I like Science! As much as the next guy, but I've watched fusion be "just a few years away" for my whole life, and I'm unconvinced. Is that being a downer or just realistic?
posted by GenjiandProust at 4:14 AM on April 16, 2013 [13 favorites]
It's also not unreasonable to point out that there are a lot of steps between a numerical simulation that shows a working design and a saleable physical product & every single one is laden with opportunities for failure. The odds on this idea making it out the other end of that pipeline is probably less than 1%.
That's not pessimism, it's realism: most research ideas don't make it. That doesn't mean we should stop doing research, it means that accepting failure is part of the deal.
posted by pharm at 4:27 AM on April 16, 2013 [1 favorite]
That's not pessimism, it's realism: most research ideas don't make it. That doesn't mean we should stop doing research, it means that accepting failure is part of the deal.
posted by pharm at 4:27 AM on April 16, 2013 [1 favorite]
It's also not unreasonable to point out that there are a lot of steps between a numerical simulation that shows a working design and a saleable physical product & every single one is laden with opportunities for failure.
There's a difference between pointing out actual issues with this particular thing (which you have done) and just hand-waving the very idea of it away and saying, "Yeah, but I bet it won't work, because stuff often doesn't work." No one needs you to say that. We know that. We've heard of stuff not working.
posted by Etrigan at 4:34 AM on April 16, 2013 [12 favorites]
There's a difference between pointing out actual issues with this particular thing (which you have done) and just hand-waving the very idea of it away and saying, "Yeah, but I bet it won't work, because stuff often doesn't work." No one needs you to say that. We know that. We've heard of stuff not working.
posted by Etrigan at 4:34 AM on April 16, 2013 [12 favorites]
It's not exactly a new idea that return on energy investment is an issue, so the fact that every time a potentially energy saving system is developed it's assumed the embedded energy in the device massively outweighs the energy saving from it is incredibly tiresome.
See, for example, people who assert that the lifecycle energy cost of a Toyota Prius is higher than that of a Cadillac Escalade, or that it'd be a waste to replace a 1909s Ford F150 that they drive 20000 miles a year.
posted by ambrosen at 4:51 AM on April 16, 2013 [1 favorite]
See, for example, people who assert that the lifecycle energy cost of a Toyota Prius is higher than that of a Cadillac Escalade, or that it'd be a waste to replace a 1909s Ford F150 that they drive 20000 miles a year.
posted by ambrosen at 4:51 AM on April 16, 2013 [1 favorite]
...there is this persistent idea that we can engineer our way out of any hole we can dig. I think that idea leads people toward "We don't need to change how we live; sure, climate change turned out to be real, but Science! will save us and our lifestyle.
Actually, that's an even larger utopian conceit. The notion that people will either willingly change their lifestyle for moral reasons, or be punished into accepting the new, moral lifestyle by fate, is wishful thinking at best.
If we can't engineer our way out of it, or provide improvements in the standard of living that make the old lifestyle obsolete, people aren't going to go for it. If it's somehow ramrodded through, you'll get a backlash that leads to reganomics or something even worse.
posted by Slap*Happy at 5:10 AM on April 16, 2013 [4 favorites]
Actually, that's an even larger utopian conceit. The notion that people will either willingly change their lifestyle for moral reasons, or be punished into accepting the new, moral lifestyle by fate, is wishful thinking at best.
If we can't engineer our way out of it, or provide improvements in the standard of living that make the old lifestyle obsolete, people aren't going to go for it. If it's somehow ramrodded through, you'll get a backlash that leads to reganomics or something even worse.
posted by Slap*Happy at 5:10 AM on April 16, 2013 [4 favorites]
We *can* engineer our way out of it. We already have solutions, some literally millenia old. But nobody is interested in implementing, they are only interested in inventing new solutions. Inventors are geniuses while implementors are drudges.
Residential heating and cooling is a major energy cost. Passive solar heating (of house and water) and cooling are well-understood technologies. But they aren't in any building codes. Putting them in there and getting a massive, WPA-like program started to rebuild homes would not only reduce our energy requirements hugely (I'm just going to throw "10%" out there as a minimum), but also reduce unemployment and jumpstart the economy.
Maybe if we called it "nano-" something people would be interested.
posted by DU at 5:23 AM on April 16, 2013 [20 favorites]
Residential heating and cooling is a major energy cost. Passive solar heating (of house and water) and cooling are well-understood technologies. But they aren't in any building codes. Putting them in there and getting a massive, WPA-like program started to rebuild homes would not only reduce our energy requirements hugely (I'm just going to throw "10%" out there as a minimum), but also reduce unemployment and jumpstart the economy.
Maybe if we called it "nano-" something people would be interested.
posted by DU at 5:23 AM on April 16, 2013 [20 favorites]
We had perfectly good technology for a lot of things in biblical times. Buy finding new, different, sometimes more complicated ways of doing things is part of human nature. We build upon knowledge, we experiment. That process has a lot of dead ends, but really I wouldn't want to live in a world where every solved problem was a closed book.
Having said that, we seem to be living in a time where innovation in building and housing is pretty much polarised between big corporate architecture projects and small-scale DIY. Between those two extremes is a big bland ocean of identikit housing. The British landscape is particularly blighted in this respect; about the only innovation going on right now is the large-scale adoption of rooftop solar, and that's got nothing to do with any change in the way we design or build our homes - it's all retrofitted.
posted by pipeski at 5:23 AM on April 16, 2013 [1 favorite]
Having said that, we seem to be living in a time where innovation in building and housing is pretty much polarised between big corporate architecture projects and small-scale DIY. Between those two extremes is a big bland ocean of identikit housing. The British landscape is particularly blighted in this respect; about the only innovation going on right now is the large-scale adoption of rooftop solar, and that's got nothing to do with any change in the way we design or build our homes - it's all retrofitted.
posted by pipeski at 5:23 AM on April 16, 2013 [1 favorite]
I've got an optical and atomic physics PhD, and so far I don't see anything dubious about the idea (though I can't access that paper. I work in industry, as a part of that pipeline that takes ideas like this from concept to product, and a lack of access to academic journals is the bane of my existence. But thanks for the figure, Pharm!)
In fact, it seems very like the technologies that are used to cool spacecraft. Radiation cooling is your only option in a vacuum, so you cover everything with mirror coating or white paint to minimize the radiation you absorb, and then add a few structures with large surface area relative to their volume, designed to radiate all the heat you can't reflect. Normally this doesn't work so well on earth, because everything is wrapped in a blanket (our atmosphere) which is going to radiate whatever heat you dump into it right back at you...
But using photonic crystals (which have absolutely already been manufactured, though not necessarily in this configuration or at large scale) does seem like it could let you concentrate the emissions in a piece of the spectrum where the atmosphere is transparent. Then radiation cooling would work as well as it does in space -- ie, not as well as active cooling like air conditioning, but better than just putting a parasol over something to shade it normally would on earth.
I think what you'd want to to do, actually, is build "fins" of this material, like the kinds of things you put on electronics that generate a lot of heat. Covering the whole roof with that would really help you radiate -- though I guess that would make it really hard to clean, depending on the scale of the fins. Maybe multi-peaked roofs, which encourage run-off as well as increasing the surface area, and spray 'em down every now and then with a fire hose?
But if you wanted to get even fancier than that, you could circulate water through them, and then down through the floors and walls of the building, and back up to the fins. That costs power now, to pump the water around, but it's probably fairly minimal compared to the compressor on an air conditioner, and you might actually get enough cooling to replace an air conditioner... I mean, assuming that you can't do that just with a single flat sheet on your flat roof. I haven't done the calculations. But what I'm saying is, if you can't get the job done with a simple configuration, it does seem to me that there would be more complicated configurations that would work.
Personally, I think this is cool, and will be forwarding this link around to people I work with. Thanks, aleph.
posted by OnceUponATime at 5:25 AM on April 16, 2013 [13 favorites]
In fact, it seems very like the technologies that are used to cool spacecraft. Radiation cooling is your only option in a vacuum, so you cover everything with mirror coating or white paint to minimize the radiation you absorb, and then add a few structures with large surface area relative to their volume, designed to radiate all the heat you can't reflect. Normally this doesn't work so well on earth, because everything is wrapped in a blanket (our atmosphere) which is going to radiate whatever heat you dump into it right back at you...
But using photonic crystals (which have absolutely already been manufactured, though not necessarily in this configuration or at large scale) does seem like it could let you concentrate the emissions in a piece of the spectrum where the atmosphere is transparent. Then radiation cooling would work as well as it does in space -- ie, not as well as active cooling like air conditioning, but better than just putting a parasol over something to shade it normally would on earth.
I think what you'd want to to do, actually, is build "fins" of this material, like the kinds of things you put on electronics that generate a lot of heat. Covering the whole roof with that would really help you radiate -- though I guess that would make it really hard to clean, depending on the scale of the fins. Maybe multi-peaked roofs, which encourage run-off as well as increasing the surface area, and spray 'em down every now and then with a fire hose?
But if you wanted to get even fancier than that, you could circulate water through them, and then down through the floors and walls of the building, and back up to the fins. That costs power now, to pump the water around, but it's probably fairly minimal compared to the compressor on an air conditioner, and you might actually get enough cooling to replace an air conditioner... I mean, assuming that you can't do that just with a single flat sheet on your flat roof. I haven't done the calculations. But what I'm saying is, if you can't get the job done with a simple configuration, it does seem to me that there would be more complicated configurations that would work.
Personally, I think this is cool, and will be forwarding this link around to people I work with. Thanks, aleph.
posted by OnceUponATime at 5:25 AM on April 16, 2013 [13 favorites]
All that said, this is pretty neat technology. I remember a few years ago I was looking up this kind of information because I wanted to make a stirling engine with the cold side being "the sky". But I couldn't figure out what wavelength I needed to radiate at or what kind of filter I'd need to block "skyglow" for lack of a better word.
posted by DU at 5:37 AM on April 16, 2013 [1 favorite]
posted by DU at 5:37 AM on April 16, 2013 [1 favorite]
So how cold will this thing get? Can't tell from the PR from Stanford, and It reflects 'most' of the incident solar radiation - around a kilowatt a square metre, tops? - so if 'most' is >90 percent, the thing will get colder and keep getting colder until, well, what? And what happens if the cleaner accidentally uses holy water and exorcises Maxwell's demon?
As for building innovation, don't forget Wikihouse (previously), which is aiming precisely to untwist the polarisation between big corporate architecture and small-scale DIY - through huge-scale DIY. That's been pushing ahead slowly but steadily;what's impressed me about it is a peculiarly practical approach backed by some serious political awareness and engagement. In particular, they're strong on the ideas that you can't in general persuade people to behave in ways that do not directly benefit them, and that in a democracy, there are serious limits to legislation and regulation in changing behaviour.
One of the key technologies that Alastair Parvin, co-founder of Wikihouse, has identified as needing to exist is what he calls 'solar-powered air conditioning for China'; aircon produces profound changes in how and where people can live, and it's not going to be possible to withhold it from those parts of the world who are aiming at Western standards of living. The environmental impact of which will also be profound - unless you find ways to give people what they want that militates against the effect. If this stuff works and is cheap and efficient to produce - and by Moore, that has killed so many promising ideas - then we may really have something splendid.
posted by Devonian at 5:48 AM on April 16, 2013 [1 favorite]
As for building innovation, don't forget Wikihouse (previously), which is aiming precisely to untwist the polarisation between big corporate architecture and small-scale DIY - through huge-scale DIY. That's been pushing ahead slowly but steadily;what's impressed me about it is a peculiarly practical approach backed by some serious political awareness and engagement. In particular, they're strong on the ideas that you can't in general persuade people to behave in ways that do not directly benefit them, and that in a democracy, there are serious limits to legislation and regulation in changing behaviour.
One of the key technologies that Alastair Parvin, co-founder of Wikihouse, has identified as needing to exist is what he calls 'solar-powered air conditioning for China'; aircon produces profound changes in how and where people can live, and it's not going to be possible to withhold it from those parts of the world who are aiming at Western standards of living. The environmental impact of which will also be profound - unless you find ways to give people what they want that militates against the effect. If this stuff works and is cheap and efficient to produce - and by Moore, that has killed so many promising ideas - then we may really have something splendid.
posted by Devonian at 5:48 AM on April 16, 2013 [1 favorite]
I suspect that you could get most of the benefit of this material by using radiative fins at night, with water or a similar material as a heat bank. Yes, it would only work at night, but the technology can be bought off the shelf. You can even run it in reverse to provide heating in winter.
posted by Joe in Australia at 5:52 AM on April 16, 2013
posted by Joe in Australia at 5:52 AM on April 16, 2013
Whoa, never heard of wikihouse. Sounds awesome, thanks for the link.
posted by DU at 5:53 AM on April 16, 2013
posted by DU at 5:53 AM on April 16, 2013
This would be perfect for living in my van.
posted by RobotVoodooPower at 5:57 AM on April 16, 2013 [3 favorites]
posted by RobotVoodooPower at 5:57 AM on April 16, 2013 [3 favorites]
We've heard of stuff not working.
Not in the World of the Futurists!
Actually, that's an even larger utopian conceit. The notion that people will either willingly change their lifestyle for moral reasons, or be punished into accepting the new, moral lifestyle by fate, is wishful thinking at best.
Moral reasons aren't necessary. When gas goes up, people reduced driving and switch to mass transit. If we stopped or reduced subsidies for petroleum production and gasoline reached the prices that it has in Europe and Japan, I expect out consumption would drop radically. The problem is not morals so much as perverse incentives.
posted by GenjiandProust at 6:03 AM on April 16, 2013 [6 favorites]
Not in the World of the Futurists!
Actually, that's an even larger utopian conceit. The notion that people will either willingly change their lifestyle for moral reasons, or be punished into accepting the new, moral lifestyle by fate, is wishful thinking at best.
Moral reasons aren't necessary. When gas goes up, people reduced driving and switch to mass transit. If we stopped or reduced subsidies for petroleum production and gasoline reached the prices that it has in Europe and Japan, I expect out consumption would drop radically. The problem is not morals so much as perverse incentives.
posted by GenjiandProust at 6:03 AM on April 16, 2013 [6 favorites]
So, this is going to make houses look like frozen dinner packs?
posted by Mitheral at 6:07 AM on April 16, 2013
posted by Mitheral at 6:07 AM on April 16, 2013
mek: "atrazine, we've already invented that, it's called washing."
I am the Viper...
posted by symbioid at 6:28 AM on April 16, 2013 [1 favorite]
I am the Viper...
posted by symbioid at 6:28 AM on April 16, 2013 [1 favorite]
The new structure accomplishes both goals. It is an effective broadband mirror for solar light – it reflects most of the sunlight.there are some problems with the practical implementation of this idea. Not only does it have to reflect light efficiently, but it has to diffuse it as much as possible (which is probably not compatible with efficiency):
In 2010 reports emerged about the "Vdara Death Ray"—concentrated reflections that burned sunbathers on the Las Vegas hotel's pool deck. In a similar case, light reflected from the facade of the Wynn hotel tower burned the roofing materials on the building's podium as they were about to be installed. Both cases involved a concave, curved facade of highly reflective glass facing the sun for part of the day. Similar problems were created by Frank Gehry's Disney Hall in Los Angeles, but not by glass; specular polished stainless-steel panels caused excessive solar glare and heat gain in adjacent buildings.posted by ennui.bz at 6:36 AM on April 16, 2013 [3 favorites]
Devonian: The modelling in the paper suggests a 100W/m^2 cooling power panel would equilibrate at 260K if the ambient air is at 300K. Wind currents (which cycle warmer air into contact with the panel) would raise that temperature a bit.
posted by pharm at 6:37 AM on April 16, 2013
posted by pharm at 6:37 AM on April 16, 2013
The problem is not morals so much as perverse incentives.
Heh. Otherwise known as incentives.
posted by 2N2222 at 7:09 AM on April 16, 2013 [2 favorites]
Heh. Otherwise known as incentives.
posted by 2N2222 at 7:09 AM on April 16, 2013 [2 favorites]
pharm, that rings bells in my head. How can something cool itself below ambient without a power source? I can happily believe the panel would dissipate heat behind it (on side A) into space (side B) and also reflect heat on side B, but side A has to be warmer than side B or there's no work for it to do.
Unless they're claiming that the cold blackness of space is the sink that "powers" it? So f you point it at the sky, ambient as far as the panel in concerned is 3K, and it just radiates all the heat it finds out to ET phone home?
Which, you know, would be absolutely NUTSO amazing if it works.
Like you could make a refrigerator by putting a panel of this on a modestly insulated crate and putting it on your porch. Or you could keep a Saharan hut cool by using this as roof tiles.
Really? Is this the claim?
Kind of a big deal if it works.
posted by seanmpuckett at 7:22 AM on April 16, 2013 [1 favorite]
Unless they're claiming that the cold blackness of space is the sink that "powers" it? So f you point it at the sky, ambient as far as the panel in concerned is 3K, and it just radiates all the heat it finds out to ET phone home?
Which, you know, would be absolutely NUTSO amazing if it works.
Like you could make a refrigerator by putting a panel of this on a modestly insulated crate and putting it on your porch. Or you could keep a Saharan hut cool by using this as roof tiles.
Really? Is this the claim?
Kind of a big deal if it works.
posted by seanmpuckett at 7:22 AM on April 16, 2013 [1 favorite]
Also it would ice over with condensate which would basically make it not work any more?
posted by seanmpuckett at 7:24 AM on April 16, 2013
posted by seanmpuckett at 7:24 AM on April 16, 2013
Car interiors that don't heat up in the summer sun.AFAIK car interiors heat up like greenhouses do, by energy radiating directly into the the interior through the glass. The sun that falls on the metal surfaces of a car has virtually no effect on the interior temperature of the car. So I don't see how this particular application is going to work. Maybe if you made one of those dashboard sun shade things out of these panels.
The panel seems like a neat idea and I'm sure there could be useful applications, but I wonder: If you're planning to go around and plaster roofs everywhere with some sort of high-tech solar panel, would we be better off just making it a PV panel, the output of which is far more versatile?
In the US, commercial buildings (including residential apartment buildings) are often constructed with flat blacktop roofs. They are leak-prone and they absorb appalling amounts of heat from the sun. But the capital costs are low, so we continue to make them. There is a laughably simple and cheap way to mitigate the heat absorption problem: reflective aluminum paint. It's so effective that it's just about a no-brainer. Yet it is far from universally deployed. Because it costs more than nothing, I guess. If you browse around Google Maps a bit, it's easy to find even cold storage facilities with flat black roofs.
My point being that there is apparently a sort of cultural problem preventing us from taking even simple, cheap steps in pursuit of lower energy costs. Businesses are run by Real MenTM and the more energy you consume the Realer you are. The challenges faced by developments like this are much steeper than they should be.
posted by Western Infidels at 7:27 AM on April 16, 2013 [6 favorites]
This would be perfect for living in my van.
Actually, this might be a good thing to put on the roof of a car. It would act as a panoramic roof, augment the car's a/c and cool the car a little when it's parked.
posted by VTX at 7:27 AM on April 16, 2013
Actually, this might be a good thing to put on the roof of a car. It would act as a panoramic roof, augment the car's a/c and cool the car a little when it's parked.
posted by VTX at 7:27 AM on April 16, 2013
Unless they're claiming that the cold blackness of space is the sink that "powers" it? So f you point it at the sky, ambient as far as the panel in concerned is 3K, and it just radiates all the heat it finds out to ET phone home? Which, you know, would be absolutely NUTSO amazing if it works.
That's the idea. It's possible to use an old-fashioned solar oven, pointed at a clear night sky, as a sort of refrigerator, which illustrates the same principle. Some people even report making ice, in cool but above-freezing temperatures. I haven't tried it myself.
posted by Western Infidels at 7:38 AM on April 16, 2013 [1 favorite]
That's the idea. It's possible to use an old-fashioned solar oven, pointed at a clear night sky, as a sort of refrigerator, which illustrates the same principle. Some people even report making ice, in cool but above-freezing temperatures. I haven't tried it myself.
posted by Western Infidels at 7:38 AM on April 16, 2013 [1 favorite]
Seanmpuckett, it is indeed "powered" by the cold blackness of space.
My question now is, photonic crystals are full of tiny holes. How do you seal them up so you can wash it without affecting performance?
posted by OnceUponATime at 7:38 AM on April 16, 2013 [1 favorite]
My question now is, photonic crystals are full of tiny holes. How do you seal them up so you can wash it without affecting performance?
posted by OnceUponATime at 7:38 AM on April 16, 2013 [1 favorite]
The sun that falls on the metal surfaces of a car has virtually no effect on the interior temperature of the car.
Oddly, that is not, in fact, the conclusion that the paper you link to reaches. What he finds is that it makes a consistent difference of 5 or 6 degrees, which he, personally doesn't care about. There are aspects of his experimental design which seem rather questionable, but there is no doubt that he finds lighter cars to be less hot than darker ones.
posted by yoink at 7:39 AM on April 16, 2013
Oddly, that is not, in fact, the conclusion that the paper you link to reaches. What he finds is that it makes a consistent difference of 5 or 6 degrees, which he, personally doesn't care about. There are aspects of his experimental design which seem rather questionable, but there is no doubt that he finds lighter cars to be less hot than darker ones.
posted by yoink at 7:39 AM on April 16, 2013
If you're planning to go around and plaster roofs everywhere with some sort of high-tech solar panel, would we be better off just making it a PV panel, the output of which is far more versatile?
PV panels require more maintence (in the electrical infrastructure if nothing else). Also the is the cost. If these things cost 1/10 of the price of a solar panel then you can do a lot more for the same money.
You are right though that people are capital cheap. Flat commercial roof are kind of stupid in a lot of ways. Ford put green roofs on some of their plants and it made a huge difference in cooling. Plus increased green space and better handling of rainwater.
posted by Mitheral at 7:41 AM on April 16, 2013
PV panels require more maintence (in the electrical infrastructure if nothing else). Also the is the cost. If these things cost 1/10 of the price of a solar panel then you can do a lot more for the same money.
You are right though that people are capital cheap. Flat commercial roof are kind of stupid in a lot of ways. Ford put green roofs on some of their plants and it made a huge difference in cooling. Plus increased green space and better handling of rainwater.
posted by Mitheral at 7:41 AM on April 16, 2013
Take an infrared thermometer, point it at the sky on a clear night. Minus 40 F or so. Point it at low clouds or fog, and it'll be closer to plus 30 F. Your location may differ, I'm near sea level on a humid cool coast. But that's about what you'll get. That's "what the thermometer sees" and is measuring how much infrared is coming from, you know, greenhouse gases between you and space.
This is how ice can be made overnight in the desert -- shallow pans left overnight (desert's generally more efficient for radiative cooling, lower humidity between you and the big deep dark); water's not the ideal material, but it works.
"Cool roof" material available now works like the nano stuff discussed, presumably not quite as well. Anything highly reflective in the visible range, and high in emissivity in the infrared, does this. Used as a dehumidifier, too.
posted by hank at 7:45 AM on April 16, 2013 [1 favorite]
This is how ice can be made overnight in the desert -- shallow pans left overnight (desert's generally more efficient for radiative cooling, lower humidity between you and the big deep dark); water's not the ideal material, but it works.
"Cool roof" material available now works like the nano stuff discussed, presumably not quite as well. Anything highly reflective in the visible range, and high in emissivity in the infrared, does this. Used as a dehumidifier, too.
posted by hank at 7:45 AM on April 16, 2013 [1 favorite]
Blacktop roofs are becoming less of an issue as well, partially through product innovation, partially through code enforcement. Some areas have "cool roof" requirements, where the roofing material has to have a solar reflection index number of some certain value so that the roof isn't absorbing a bunch of solar energy. There's also PVC and TPO roofing materials which are gaining a lot of traction just because they're way easier to install than hot-mop bitumen, and those materials are completely, blindingly white.
As far as keeping these panels clean, there have been developments recently for "self cleaning windows" that are coated with some sort of nano-surface such that they're effectively washed by rainwater.
posted by LionIndex at 7:49 AM on April 16, 2013
As far as keeping these panels clean, there have been developments recently for "self cleaning windows" that are coated with some sort of nano-surface such that they're effectively washed by rainwater.
posted by LionIndex at 7:49 AM on April 16, 2013
One kind of odd thing I've noticed up here in canuckistan is frost shadows, which are probably similar deals to the way this works.
On cool clear nights we'll get frost on the grass, except where objects shade the grass from the night sky, like trees or benches or whatnot.
I'm not talking about actual shadows where frost has not melted due to the sun burning the rest of the frost away; these kind of frost shadows I am talking about appear when the sun is not shining at all.
I have an IR thermometer I shall have to try pointing it at the sky at night, that sounds neat.
posted by seanmpuckett at 7:54 AM on April 16, 2013 [1 favorite]
On cool clear nights we'll get frost on the grass, except where objects shade the grass from the night sky, like trees or benches or whatnot.
I'm not talking about actual shadows where frost has not melted due to the sun burning the rest of the frost away; these kind of frost shadows I am talking about appear when the sun is not shining at all.
I have an IR thermometer I shall have to try pointing it at the sky at night, that sounds neat.
posted by seanmpuckett at 7:54 AM on April 16, 2013 [1 favorite]
"..The odds on this idea making it out the other end of that pipeline is probably less than 1%.."
I disagree. The odds of it supplanting other technologies and taking up large swaths of shelf space at Home Depot are naturally remote, there can only be one winner there, but that doesn't preclude being developed and sold in places and ways you might never know or hear about for niche applications, military, space, 3rd world etc..
posted by stbalbach at 8:05 AM on April 16, 2013 [1 favorite]
I disagree. The odds of it supplanting other technologies and taking up large swaths of shelf space at Home Depot are naturally remote, there can only be one winner there, but that doesn't preclude being developed and sold in places and ways you might never know or hear about for niche applications, military, space, 3rd world etc..
posted by stbalbach at 8:05 AM on April 16, 2013 [1 favorite]
OLEDs have been at least twenty years in the making, to the point that they're a competitive technology in a mature market. Many of the problems holding them back, including basic manufacturing, device life, packaging, contamination and so on, have yet to be completely fixed in general, and in particular are still holding them back from some major uses. Elsewhere, they're 'good enough' to be profitable to make, even though they haven't actually won any large niches from LCDs in the way that e-ink has.
Nanomaterial passive cooling will have its own sets of problems, some of which they'll share with OLEDs, on its way to wherever it might get to if it becomes commercially interesting. There's a rule of thumb that any new materials technology takes around ten years from the first public lab demo of it actually doing what you want it to, to the point that you have an achievable point on the roadmap where people might give you money for a finished product. Some things are quicker (I think giant magnetoresistivity made it from first discovery to product a little faster, but that's a special case for lots of reasons); others never really make it at all - I cannot remember how many demonstrations I've had over the same two decades of consumer-oriented fuel cells, all "18 to 24 months away from production, sir". And other factors conspire aplenty; UWB never made it despite being quite a simple extension of established technologies with a really compelling set of use cases, and I'm still not quite sure why. Industry shenanigans, I think. Some, like WiMAX, are inventions of the industry desperately trying to find new markets and magically thinking that PowerPoint can become reality just because. And I'm not even going to get into the 'flash killer' universal memory game.
If you google for nanomaterial cooling, you'll find a whole host of similar (and different) ideas out there. One thing can be guaranteed - most of these will not make it.
posted by Devonian at 8:46 AM on April 16, 2013
Nanomaterial passive cooling will have its own sets of problems, some of which they'll share with OLEDs, on its way to wherever it might get to if it becomes commercially interesting. There's a rule of thumb that any new materials technology takes around ten years from the first public lab demo of it actually doing what you want it to, to the point that you have an achievable point on the roadmap where people might give you money for a finished product. Some things are quicker (I think giant magnetoresistivity made it from first discovery to product a little faster, but that's a special case for lots of reasons); others never really make it at all - I cannot remember how many demonstrations I've had over the same two decades of consumer-oriented fuel cells, all "18 to 24 months away from production, sir". And other factors conspire aplenty; UWB never made it despite being quite a simple extension of established technologies with a really compelling set of use cases, and I'm still not quite sure why. Industry shenanigans, I think. Some, like WiMAX, are inventions of the industry desperately trying to find new markets and magically thinking that PowerPoint can become reality just because. And I'm not even going to get into the 'flash killer' universal memory game.
If you google for nanomaterial cooling, you'll find a whole host of similar (and different) ideas out there. One thing can be guaranteed - most of these will not make it.
posted by Devonian at 8:46 AM on April 16, 2013
Inventors are geniuses while implementors are drudges.
Residential heating and cooling is a major energy cost. Passive solar heating (of house and water) and cooling are well-understood technologies. But they aren't in any building codes. Putting them in there and getting a massive, WPA-like program started to rebuild homes would not only reduce our energy requirements hugely (I'm just going to throw "10%" out there as a minimum), but also reduce unemployment and jumpstart the economy.
Maybe if we called it "nano-" something people would be interested.
Oh my god can I favorite this a thousand times? Nano-metric-ultra-fluro solutions are the craze when most people haven't even hung curtains, took the time to get efficient windows installed, or cleaned their air conditioner coils.
As a down to earth engineer that cares about the environment and wants all these good things to happen so that we don't end up passing a world with much reduced awesome factor, and utility for that matter, to our children, the cynic in me means I've learned that I have to walk away from conversations like this but DU nailed it.
I'm going to turn my compost and sort my recycling when I get home. Kudos if you do something in the same vein.
posted by RolandOfEld at 9:22 AM on April 16, 2013 [1 favorite]
Residential heating and cooling is a major energy cost. Passive solar heating (of house and water) and cooling are well-understood technologies. But they aren't in any building codes. Putting them in there and getting a massive, WPA-like program started to rebuild homes would not only reduce our energy requirements hugely (I'm just going to throw "10%" out there as a minimum), but also reduce unemployment and jumpstart the economy.
Maybe if we called it "nano-" something people would be interested.
Oh my god can I favorite this a thousand times? Nano-metric-ultra-fluro solutions are the craze when most people haven't even hung curtains, took the time to get efficient windows installed, or cleaned their air conditioner coils.
As a down to earth engineer that cares about the environment and wants all these good things to happen so that we don't end up passing a world with much reduced awesome factor, and utility for that matter, to our children, the cynic in me means I've learned that I have to walk away from conversations like this but DU nailed it.
I'm going to turn my compost and sort my recycling when I get home. Kudos if you do something in the same vein.
posted by RolandOfEld at 9:22 AM on April 16, 2013 [1 favorite]
(Yah...DU nails it a lot)
...or situated the house properly on the lot, or planted a tree, or set up a breezway, or painted the roof/roads/anything black white, etc etc.
That being said, this does sound pretty neat...I wonder if this could be done with just a pigment, though...like the way fluorescent paint translates UV to visible light...
Personally though, I think the best solution is just a (near-total) ban on AC. It's a losing game.
posted by sexyrobot at 9:36 AM on April 16, 2013 [1 favorite]
...or situated the house properly on the lot, or planted a tree, or set up a breezway, or painted the roof/roads/anything black white, etc etc.
That being said, this does sound pretty neat...I wonder if this could be done with just a pigment, though...like the way fluorescent paint translates UV to visible light...
Personally though, I think the best solution is just a (near-total) ban on AC. It's a losing game.
posted by sexyrobot at 9:36 AM on April 16, 2013 [1 favorite]
I think what you'd want to to do, actually, is build "fins" of this material
Not fins. I'd think you'd want to maximize solid angle view of the sky, and minimize surface area conducting heat from the air. So a flat plate (or something dome shaped because there's probably a sin theta in there somewhere).
Two of these magic surfaces facing each other (as with fins) won't do anything.
posted by ryanrs at 9:56 AM on April 16, 2013
Not fins. I'd think you'd want to maximize solid angle view of the sky, and minimize surface area conducting heat from the air. So a flat plate (or something dome shaped because there's probably a sin theta in there somewhere).
Two of these magic surfaces facing each other (as with fins) won't do anything.
posted by ryanrs at 9:56 AM on April 16, 2013
But this is the problem that Wikihouse gets, and so many other people do not. The sensible, effective, if-everyone-did-them ways of modifying one's life to reduce energy usage and environmental footprint, are just not attractive enough to do much good. Or if they are, they're in the way of established and commercially forceful choices that have en enormous amount of economic and cultural inertia.
Banning AC is exactly that sort of thing. You can engineer AC to be unattractively expensive to use, and you can tweak the rules about the boundaries of acceptable usage, but how well would a ban go down in Florida? It'd empty the state. Hugely increasing the cost of energy would do it, but would have plenty of unpleasant if not dangerous consequences, especially for the poor.
We are, and always have been, a species in symbiotic thrall to our technology. As we are pretty poor at engineering ourselves to be 'better' citizens of a shared planet, the two main ways forward are either through technology or through three-key-reset disasters that aren't quite bad enough to actually take away our ability to make better technology - followed by social reform and, yes, better technology. A technophile, I went through a period of agreeing that the 'new technology will fix stuff' idea was romantic, deluded and dangerous, which corresponded roughly to my deep green period. That's still not over - living off-the-grid is still a lovely idea for me and it's largely achievable (even while keeping my urban-based economic and social life, albeit modified). But I haven't done it yet which shows you how much I want it.
People do not want to go backwards. They do not want even the appearance of going backwards. They want their jetpacks. If you want to wean them off that without having some global collapse do it the hard way, you have to follow the way smoking is being run out of town, but with a far, far more difficult argument to make as to why.
Looking for better technology to support a preferred lifestyle is the best way forward, not because Technology Is Magic and fixes things without problems - we learned that this wasn't the case last century. It's the best way forward because that's how humans work, given the choice, and we don't have any acceptable ways to change the way people are. We learned that last century, too.
posted by Devonian at 10:14 AM on April 16, 2013 [1 favorite]
Banning AC is exactly that sort of thing. You can engineer AC to be unattractively expensive to use, and you can tweak the rules about the boundaries of acceptable usage, but how well would a ban go down in Florida? It'd empty the state. Hugely increasing the cost of energy would do it, but would have plenty of unpleasant if not dangerous consequences, especially for the poor.
We are, and always have been, a species in symbiotic thrall to our technology. As we are pretty poor at engineering ourselves to be 'better' citizens of a shared planet, the two main ways forward are either through technology or through three-key-reset disasters that aren't quite bad enough to actually take away our ability to make better technology - followed by social reform and, yes, better technology. A technophile, I went through a period of agreeing that the 'new technology will fix stuff' idea was romantic, deluded and dangerous, which corresponded roughly to my deep green period. That's still not over - living off-the-grid is still a lovely idea for me and it's largely achievable (even while keeping my urban-based economic and social life, albeit modified). But I haven't done it yet which shows you how much I want it.
People do not want to go backwards. They do not want even the appearance of going backwards. They want their jetpacks. If you want to wean them off that without having some global collapse do it the hard way, you have to follow the way smoking is being run out of town, but with a far, far more difficult argument to make as to why.
Looking for better technology to support a preferred lifestyle is the best way forward, not because Technology Is Magic and fixes things without problems - we learned that this wasn't the case last century. It's the best way forward because that's how humans work, given the choice, and we don't have any acceptable ways to change the way people are. We learned that last century, too.
posted by Devonian at 10:14 AM on April 16, 2013 [1 favorite]
I think there's room for a little stick with the carrot. I wonder if it'd be feasible to regulate real estate sales so that people had to list the 30 year energy cost of the homes they sell based on their actual usage. This would force people to either make the capital improvements to keep energy costs low, or fake it by living more simply and not running the AC 24-7.
posted by BrotherCaine at 10:33 AM on April 16, 2013 [1 favorite]
posted by BrotherCaine at 10:33 AM on April 16, 2013 [1 favorite]
As a renter, I'd appreciate knowing energy efficiency ahead of time too.
posted by BrotherCaine at 10:34 AM on April 16, 2013 [1 favorite]
posted by BrotherCaine at 10:34 AM on April 16, 2013 [1 favorite]
When gas goes up, people reduced driving and switch to mass transit.
No, they didn't. People bought more fuel efficient SUV's, and ramped up oil production using controversial new technologies and pipeline construction. Urban transit infrastructure is so neglected, urban cycling went from an extreme sport like slacklining and buildering to a mainstream commuting lifestyle.
People are going to pervert whatever incentive you got.
posted by Slap*Happy at 11:56 AM on April 16, 2013 [1 favorite]
No, they didn't. People bought more fuel efficient SUV's, and ramped up oil production using controversial new technologies and pipeline construction. Urban transit infrastructure is so neglected, urban cycling went from an extreme sport like slacklining and buildering to a mainstream commuting lifestyle.
People are going to pervert whatever incentive you got.
posted by Slap*Happy at 11:56 AM on April 16, 2013 [1 favorite]
Article is interesting. It doesn't break thermodynamics because it doesn't actually reduce temperature itself, it just reflects sunlight away really well thus helping to keep the structure from getting much warmer, and it radiates heat away at a wavelength that doesn't get caught in the atmosphere, allowing natural heat dissipation to be more effective.
No, they didn't.
God. The problem with conversations like this is words like people and they get thrown around, as nebulous, handwavy terms allowing the speaker to describe everyone in a class, as if their actions could be infallibly categorized together as belonging to a single cohesive entity. Populations are more complex than that.
Actually, both things happened. Some people did reduce driving. And also, some people got more fuel-efficient vehicles, and some companies started using new oil production technologies. If gas prices get much higher, eventually these equilibriums will break, and people will have to drive less, because edge cases will become more relevant, and not all problems have solutions. "People" won't be able to pervert anything then -- but people will also be lucky if they can get what we regard now as ordinary, day-to-day activities done, and (if you're not wealthy) lifestyles will have to shift to accommodate that.
There might be other solutions, and some of them might be good and some might be bad. We don't know. But suggesting that people will always find the worst solution is basically appeal to inertia.
If we can't engineer our way out of it, or provide improvements in the standard of living that make the old lifestyle obsolete, people aren't going to go for it. If it's somehow ramrodded through, you'll get a backlash that leads to reganomics or something even worse.
This is only partially true, for as with most things it's a matter of degree, the point where two lines on a graph meet. People do change their behavior, sometimes, for moral reasons, if it's not too much trouble or too expensive. The thing is that point, the break point where they change their behavior, isn't fixed. It's variable depending on other factors, like the public perception of the problem, the media coverage of it, economic and political factors, how much they can afford to change, and even how harried they are in their lives.
The factors that lead people to actually make changes to their lives are chaotic. It'd be nice, yes, if they would do good things for altrustic reasons more often. But saying they'll never do this is doing them a disservice, and, again, appeal to inertia: it'll never work, so don't try anything.
posted by JHarris at 12:27 PM on April 16, 2013 [4 favorites]
No, they didn't.
God. The problem with conversations like this is words like people and they get thrown around, as nebulous, handwavy terms allowing the speaker to describe everyone in a class, as if their actions could be infallibly categorized together as belonging to a single cohesive entity. Populations are more complex than that.
Actually, both things happened. Some people did reduce driving. And also, some people got more fuel-efficient vehicles, and some companies started using new oil production technologies. If gas prices get much higher, eventually these equilibriums will break, and people will have to drive less, because edge cases will become more relevant, and not all problems have solutions. "People" won't be able to pervert anything then -- but people will also be lucky if they can get what we regard now as ordinary, day-to-day activities done, and (if you're not wealthy) lifestyles will have to shift to accommodate that.
There might be other solutions, and some of them might be good and some might be bad. We don't know. But suggesting that people will always find the worst solution is basically appeal to inertia.
If we can't engineer our way out of it, or provide improvements in the standard of living that make the old lifestyle obsolete, people aren't going to go for it. If it's somehow ramrodded through, you'll get a backlash that leads to reganomics or something even worse.
This is only partially true, for as with most things it's a matter of degree, the point where two lines on a graph meet. People do change their behavior, sometimes, for moral reasons, if it's not too much trouble or too expensive. The thing is that point, the break point where they change their behavior, isn't fixed. It's variable depending on other factors, like the public perception of the problem, the media coverage of it, economic and political factors, how much they can afford to change, and even how harried they are in their lives.
The factors that lead people to actually make changes to their lives are chaotic. It'd be nice, yes, if they would do good things for altrustic reasons more often. But saying they'll never do this is doing them a disservice, and, again, appeal to inertia: it'll never work, so don't try anything.
posted by JHarris at 12:27 PM on April 16, 2013 [4 favorites]
After lurking for many (10? 12?) years I figured I owed Mefi the $5 - especially now that there's a post about my work! Seriously, it's very exciting to see a link to one's work (especially when you're a PhD student..) on a daily read.
I'm one of the authors of the paper, and I'm glad a lot of you found it cool as well. We're working on building the actual prototype right now and will be tackling many of the challenges that came up in the comments.
A lot of the early work in night-time radiative cooling (in the 70s and 80s) was motivated by applications for the rural developing world, and funded by development grants. I think that application opportunity still exists if we can do this very cheaply. I've traveled a bit in rural West Africa and, among other examples, vaccine/medicine refrigeration in rural clinics remains a big problem.
If you'd like a copy of the paper, please memail me your email address and I can send it to you.
posted by strangeloops at 12:36 PM on April 16, 2013 [29 favorites]
I'm one of the authors of the paper, and I'm glad a lot of you found it cool as well. We're working on building the actual prototype right now and will be tackling many of the challenges that came up in the comments.
A lot of the early work in night-time radiative cooling (in the 70s and 80s) was motivated by applications for the rural developing world, and funded by development grants. I think that application opportunity still exists if we can do this very cheaply. I've traveled a bit in rural West Africa and, among other examples, vaccine/medicine refrigeration in rural clinics remains a big problem.
If you'd like a copy of the paper, please memail me your email address and I can send it to you.
posted by strangeloops at 12:36 PM on April 16, 2013 [29 favorites]
welcome strangeloops and thanks for working to make the world a better place.
posted by stbalbach at 4:48 PM on April 16, 2013
posted by stbalbach at 4:48 PM on April 16, 2013
Maybe if we called it "nano-" something people would be interested.
The United States already has so many nano solutions for big problems that it for all intents and purposes is a homeopathic government.
posted by srboisvert at 1:19 PM on April 17, 2013
The United States already has so many nano solutions for big problems that it for all intents and purposes is a homeopathic government.
posted by srboisvert at 1:19 PM on April 17, 2013
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Of course, it will turn out that making these panels requires vast amounts of electricity and rare materials, and the panels will release deadly gases when they decay.
posted by pracowity at 2:06 AM on April 16, 2013 [8 favorites]